On Thursday, December 13, 2012 4:14:23 AM UTC-8, Marshall Bockrath-Vandegrift wrote:
> kristianlm <kris...@adellica.com <javascript:>> writes: > > > I'm enjoying testing Java code with Clojure and it's been a lot of fun > > so far. Coming from Scheme, the transit is comfortable. However, I > > encountered a big surprise when I nested def's and used them with a > > proxy: > > This is a common surprise for people with previous exposure to Scheme: > `def` in Clojure is always explicitly namespace-scoped. What it does is > create a var with a name and intern it into the namespace with that > name, not introduce a name in the current lexical scope. Nested `def`s > are thus very rarely going to be what one actually want, and the > behavior you’re seeing is exactly what one would expect. > > To further clarify: the mew* version doesn't *actually* behave just like new-let*, although it usually will have the same consequences. The issue is that there's a race condition if two different threads call mew* at the same time: they might both mutate i, then both read it, and thus end up with the same reference. Really, as Marhsall says, a nested def is (almost) never what you want. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
